Quote:
Originally Posted by cbale2000
On the note of using PVC, generally speaking I agree that PVC should be avoided, especially for the accumulator (air storage), but to be honest there is far less pressure involved for a much shorter amount of time when using PVC for the barrel of a cannon. IMO if you're really that concerned about it, and can't get a suitable pressure-rated metal tube, build a small polycarbonate (or whatever) box around the bottom half of the barrel to catch shrapnel in the event of a failure. Lots of teams have built PVC t-shirt cannons and no one has died yet (that we know of).
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*gets up on soapbox*
1> The pressure in the barrel is enough to fire the t-shirt, thus it is enough to fire PVC shards.
2> A box around the lower half of a PVC cannon
might help. Are you willing to risk your students (or worse the public) should you be wrong?
3> As to your last line -- does someone need to die to get people to stop using PVC in gas pressure applications?
As an engineer, you need to always understand how safe your product is. T-shirt cannons, by their very nature, will be used near the public. If the t-shirt can reach the crowd, so can shards from a sundered barrel.
JM(NS)HO
*gets off soapbox*